Reddit user PumpkinSpice210 believes the third season will use police interviews surrounding Tyler Down's attempted shooting as the narrative structure that pulls the audience between the past and present. Her theory hinges on Montgomery de la Cruz stepping into the role of the Big Bad now that Bryce Walker has transferred. The questioned students would grapple with the morality of telling the truth or protecting Tyler, whose fragile state is a product of Monty's bullying.
We like this theory because it has the potential to include all of our key players and allows the story to pick up where we left off. Moreover, her theory dovetails nicely with Twitter user DanLynch94, who suggests the third season will move forward with another old school method of communication, VHS tapes. While we think the distribution of actual videotapes is a little gimmicky, the idea that the police interviews may occur on video is a nice addition to the theory that we'll gladly adopt.
Another possibility for the season three structure is the creators could reboot the series with a whole new set of characters and challenges to overcome. While this is highly unlikely due to the popularity of the cast, we can't rule the idea out since the same approach was taken for the third season of MTV's Scream . . . and no one in the 13 Reasons Why cast is getting any closer to high school-aged.